Independent reviewers believe that NASA’s James Webb Space Telescope could be on a path that would lead to more schedule delays and, consequently, the possibility of added costs.

You’ll recall, the space agency’s next great space telescope was originally estimated to cost taxpayers as little as $1 billion and blast off on a mission to study the evolution of galaxies between 2007 and 2011. Now, the cost estimate is about $9 billion and the launch target is late 2018. After an exhaustive review of the project, and harsh criticism from Congress, NASA overhauled the telescope management and promised Webb was back on track.

A new report, mandated by skeptical members of Congress and made public this week, indicates NASA has made progress on getting the telescope’s cost and schedule under control. Some “best practices” long suggested by the U.S. Government Accountability Office are being abided by the new management of the Webb project. But, alas, some best practices are not.

First, the project has what could be too little time and money set aside for unexpected challenges in the development of perhaps one of the most complicated spacecraft NASA has ever flown. In the space business, time is money. If NASA must delay the launch into 2019, which is likely given the historical record, every few months could cost taxpayers hundreds of millions of dollars. Already, there are substantial issues with several instruments, some of which could cause additional testing or even reconstruction of some components.

Among the chief concerns of the GAO review: too large a share of the final testing of the spacecraft, upon assembly and before flight, is jammed into the final year or so of its schedule.

A too-tight window remains for problems that inevitably crop up with these big space projects. Without saying it in these terms, the GAO is finding that NASA continues to have a rosy outlook on its ability to deliver on a series of incredibly difficult tasks and overcome challenges without much time delay.>